Forum Discussion

Copper Contributor

Jul 09, 2020

Limit Windows Defender CPU Usage

I have the problem that our Clients use too much CPU during a FullScan. Actually, the usage is limited to 20%, but the setting seems to have no effect. Whether I set it via Configuration Manager or G...

Copper Contributor

Oct 14, 2020

philippwree We have the same issue, CPU limit is completely ignored. Is there a solution anywhere? iv been searching but cant find anything usefull

mongrel15
Copper Contributor
Oct 14, 2020
Daniel_Larsson In your antimalware policy under “Scheduled Scans”, switch the option “Start a scheduled scan only when the computer is idle” to no. That solved the problem for us.
It seems that the check by Microsoft is flawed. If Endpoint thinks the system is idle, he ignores the CPU limit.
- AJP123
  Copper Contributor
  Jan 15, 2021
  mongrel15
  Changing the following setting to NO doesn't make any difference for us - "Start a scheduled scan only when the computer is idle” / "“ScanOnlyIfIdle” doesn't make any difference for us.
  
  I tried setting "AvgCPULoadFactor"n in the registry to 1% and it would still hit up to 68%.
  - Salbert89
    Copper Contributor
    Apr 13, 2021
    AJP123
    Hey,
    based on the docs article for Set-MpPreference, its not a hard limit, see text below.
    
    https://docs.microsoft.com/en-us/powershell/module/defender/set-mppreference?view=windowsserver2019-ps&viewFallbackFrom=win10-ps
    
    -ScanAvgCPULoadFactor
    Specifies the maximum percentage CPU usage for a scan. The acceptable values for this parameter are: integers from 5 through 100, and the value 0, which disables CPU throttling. Windows Defender does not exceed the percentage of CPU usage that you specify. The default value is 50.
    Note: This is not a hard limit but rather a guidance for the scanning engine to not exceed this maximum on average.

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